1. Field of the Invention
This invention relates to systems for controlling vehicle traffic signals to allow safe passage of emergency vehicles and more particularly relates to a system for autonomously preempting traffic signals at an intersection that includes a vehicle transponder, a real-time intersection controller and monitor (with an intersection-based visual and/or audio alarm warning system), an operations display and control software, and a wide-area communications network.
2. Background Information
Present systems used to preempt traffic signals and clear intersections for emergency vehicles responding to a life-saving event often come with severe limitations. They rely on: sound activation, optical activation, direct microwave activation, and a combination of all the above. All of these systems have severe operational limitations affected by weather, line of sight, and critical range. These systems often have further drawbacks requiring them to be activated by the emergency vehicle operator or first responder (herein referred to as “e-operator”). These systems also severely disrupt the normal phasing patterns of a traffic controller's nominal programming because these systems do not provide real-time monitoring of intersection phases or timing.
Emergency vehicles currently rely on vehicle horn, sirens, and flashing lights to prevent accidental collisions with pedestrians or other vehicles at intersections. E-operators must focus all their attention on driving the vehicles. Other preemption systems fail to provide visual or audio feedback systems (to either motorists or e-operators) that are physically located in the intersection (herein referred to as “intersection-based warnings”). Such preemption systems compromise motorist and e-operator safety, as there is no awareness of a traffic-light preemption event (referred herein as “silent preemption”). Additionally, these systems fail to provide real-time feedback to e-operators through warning devices inside their vehicles (herein referred to as “vehicle-based warnings”). These factors have the effect that e-operators do not get the feedback required and soon stop using the system.
An intersection-based preemption system that provides feedback and is activated autonomously by an approaching emergency vehicle is needed. Such a system overcomes some of the drawbacks of available systems. Intersection-based visual warnings are proven effective for motorists, and are also critically important to e-operators when multiple emergency vehicles are approaching the same intersections (referred herein as “conflict detection”). These displays are directly in their field-of-vision and e-operators are immediately aware of potential conflicts. Human factors studies often refer to such indicators as “real-world”. Intersection-based warnings combined with autonomous activation removes the distraction by keeping drivers' eyes on the road.
A system is needed that takes special consideration of pedestrians. Visual intersection-based warnings may fail to get the attention of pedestrians standing near an intersection. For this reason, audible alerts in addition to visual may be the most effective (and rapid) warning system of the approach of emergency vehicles. There is also the difficulty that pedestrians may often be in harms way if they fail to hear an approaching emergency vehicle. Although vehicle sirens are especially loud, many circumstances can lead to dangerous situations and potential injury. For instance, an especially long crosswalk may take up to 20 seconds to cross. In that time, an emergency vehicle may be heard, perhaps stranding the pedestrian in the middle of a crosswalk. Likewise, in extremely busy metropolitan intersections, ambient noise in the building occlusions may prevent warning of the emergency vehicle until just seconds before the vehicle arrived at an intersection. A system is needed that disables normal pedestrian clearance at intersections long before actual preemption has been triggered (herein referred to as “pedestrian-inhibit”). This system would greatly enhance the safety of emergency vehicle preemption by preventing pedestrians from entering an intersection long before a vehicle arrives (or can be seen or heard).
Existing preemption systems provide little or no visibility, configuration control, or remote interaction with their operation or function. A system is needed that provides real-time feedback, monitoring, logging, and control of vehicle and intersection preemption-related data. This data would be displayed at both mobile stations and central operation center(s). Additionally, a system is needed that provides secure, robust transfer of data to/from intersections, vehicles, and operation center(s) using either wireless or LAN architectures. All of these functions enable logistical commanders and traffic management authorities to coordinate, configure, and monitor activity in the overall preemption network.
It is one object of the present invention to provide an emergency vehicle traffic signal preemption system that is fully autonomous and not dependent on the intersection being in visual range.
Still another object of the present invention is to provide an emergency vehicle traffic signal preemption system that includes a real-time monitor of intersection phase to optimize triggers and timing for both preempt and pedestrian-inhibit functions. This includes minimizing disruption of normal traffic controller behavior and sequencing.
Still another object of the present invention is to provide an emergency vehicle traffic preemption system that includes visual displays in the intersections (and interfaces to such displays) indicating direction and location of approaching emergency vehicle(s).
Still another object of the present invention is to provide an emergency vehicle traffic signal preemption system that provides conflict detection (between emergency vehicles and e-operators) and alerts other emergency vehicles in the area. This conflict detection is provided in two forms: intersection-based warnings and vehicle-based warnings.
Still another object of the present invention is to provide an emergency vehicle traffic signal preemption system that includes a pedestrian audio warning signal to supplement the intersection-based visual display and the audio signals from emergency vehicles.
Yet another object of the present invention is to provide an emergency vehicle preemption system having an autonomous emergency vehicle transponder including an on-board diagnostic (OBD) interface, a real-time navigation interface and position estimation module, and a communications monitor and control interface.
Still another object of the present invention is to provide an emergency vehicle traffic signal preemption system that allows real-time remote access, monitoring, and tracking of the entire preemption system via secure wide-area networks (wireless and LAN). This includes access to the operations display and control software (herein referred to as “operations software”) from management centers (TMC, 911-call center, etc.), mobile commanders, as well as individual emergency responder vehicles.